Intramolecular hydrogen-bond activation for the addition of nucleophilic imines: 2-hydroxybenzophenone as a chemical auxiliary

The addition of nucleophilic imines, using 2-hydroxybenzophenone as a chemical auxiliary, is presented. An intramolecular six-membered ring via hydrogen bonding that enhances the reactivity and selectivity is the key of this strategy, which is supported by DFT calculations and experimental trialsSpanish Government (CTQ2015-64561-R, CTQ2016-76061-P, and MDM-2014-0377), Prodep (UJAT-PTC-247) and CCC-UAM are acknowledged. A. G. thanks MINECO for a PhD fellowship (FPI) and A. M. S. thanks CAM for a postdoctoral contract (2016-T2/IND-1660

Modelación del frijol en Latinoamérica: Estado del arte y base de datos para parametrización

Frijol común (Phaseolus vulgaris L.) es la leguminosa de grano para consumo humano de mayor producción en el mundo, y es nativo de las Américas, donde juega un papel importante en la dieta. Los ambientes donde se cultiva el frijol varían desde zonas tropicales hasta alta montaña, con diversos hábitos de crecimiento (arbustivo determinado, arbustivo indeterminado, y voluble), y en sistemas de producción desde los tradicionales hasta los altamente tecnificados. Los esfuerzos en modelaje, por tanto, deben empezar desde identificar el tipo de frijol y el sistema objetivo. El frijol es muy sensible al estrés abiótico, hecho que ha animado el modelaje de su posible respuesta bajo escenarios de cambio climático. Se llevó a cabo una revisión de literatura para identificar quince ejercicios de modelaje ejecutados en América Latina, abarcando estudios de crecimiento (tazas de producción de nudos y área foliar), fenología, y de rendimiento. Los modelos empleados en dichos estudios incluyen EcoCrop, CROPGRO-DRYBEAN (implementado en la plataforma DSSAT), y en un caso cada uno, Maxent y CLIMEX. Se describen cuatro estudios en detalle: en los dos países de mayor producción en el mundo (Brasil y México), y en Centroamérica como región altamente vulnerable al cambio climático. Estos estudios concuerdan que la productividad del frijol podría sufrir serios efectos negativos en el transcurso del Siglo XXI a raíz del cambio climático. Finalmente, se informa sobre un ejercicio reciente de recopilar datos históricos de ensayos de frijol en Latinoamérica para alimentar futuros esfuerzos de modelaje. Common bean (Phaseolus vulgaris L.) is the grain legume of greatest volume of production for direct human consumption, and is native to the Americas where it plays an important role in the diet of consumers. Bean is cultivated in environments from lowland tropical areas to high mountainous zones; with growth habits ranging from determinate bush, to indeterminate bush, to climbing types; and in production systems varying from traditional low input agriculture to highly technified systems. As such, efforts at modelling should focus on a specific plant type and production system. Bean is very sensitive to abiotic stress, a fact that has motivated modelling of its response in light of the dangers of climate change. A review of literature was carried out revealing fifteen studies in Latin America considering different aspects of plant growth (rates of node and leaf area production), phenology, and yield. Models employed include EcoCrop, CROPGRO (a module within the DSSAT cropping system model), and in one instance each, Maxent and CLIMEX. Three studies in particular are detailed: in the two countries of greatest production in the world (Brazil and Mexico), and one study in Central America as a region under direct threat of climate change. These three studies confirm that bean productivity will likely suffer severe negative effects in the course of the 21st century, as a result of climate change. A recent effort has compiled data from historical yield trials in Latin America as a resource for future modelling efforts.JRC.D.5-Food Securit

Facile solventless synthesis of a nylon-6,6/silver nanoparticles composite and its XPS study

SINTESIS DE NANOPARTICULASSilver nanoparticles were synthesized and supported on thin nylon membranes by means of a simple method of impregnation and chemical reduction of Ag ions at ambient conditions. Particles of less than 10nm were obtained using this methodology, in which the nylon fibers behave as constrained nanoreactors. Pores on nylon fibres along with oxygen and nitrogen from amide moieties in nylon provide effective sites for in situ reduction of silver ions and for the formation and stabilization of Ag nanoparticles. Transmission electron microscopy (TEM) analysis showed that silver nanoparticles are well dispersed throughout the nylon fibers. Furthermore, an interaction betweenUAEME

Article Germacrone Derivatives as new Insecticidal and Acaricidal Compounds: A Structure-Activity Relationship

The supplementary material related to this article includes NMR spectra of new compounds is available online at https://www.mdpi.com/1420-3049/24/16/2898/s1.Currently, the use of synthetic pesticides is the main method of plant protection applied in agri- and horticulture. However, its excessive use leads to the development of pesticide resistance, a contamination of the environment, toxicity to non-target organisms, and risks for human health. With the ultimate aim of contributing to the develop of a more sustainable pest management, we used the natural product germacrone (compound 1), reported to possess significant insecticidal activity, as starting material for the generation of molecular diversity (2–24). Some of the generated derivatives are natural compounds, such as 1,10-epoxygermacrone (2), 4,5-epoxygermacrone (3), gajutsulactone A (7), germacrol (11), isogermacrone (14), 9-hydroxyeudesma-3,7(11)dien-6-one (19), eudesma-4,7(11),dien-8-one (20), eudesma-3,7(11)-dien-8-one (21) and eudesma-4(15),7(11)-dien-8-one (22). Compounds, 7,11-9,10-diepoxigermacr-4,5-en-8-ol (17), 7,11-epoxieudesma-4,7(11)-dien-8-one (23) and 7,11-epoxieudesma-3,7(11)-dien-8-one (24) are described for the first time. The biocidal activity of most of these compounds was assayed against the tick Hyalomma lusitanicum. The acaricidal effects of compound 24 were four times higher than that of germacrone (1). Compound 2 is an insect antifeedant a thousand times more potent than germacrone against Rhopalosiphum padi, which makes this substance a promising selective antifeedant against this cereal pest.This research was funded by Grant CTQ-2015-64049-C3-3-R/CTQ2015-64049-C3-1-R; MINISTERIO DE ECONOMÍA Y COMPETITIVIDAD, Spain (MINECO/FEDER)

Emergence of the Stoner-Wohlfarth astroid in thin films at dynamic regime

The Stoner-Wohlfarth (SW) model is the simplest model that describes adequately the magnetization reversal of nanoscale systems that are small enough to contain single magnetic domains. However for larger sizes where multi-domain effects are present, e.g., in thin films, this simple macrospin approximation fails and the experimental critical curve, referred as SW astroid, is far from its predictions. Here we show that this discrepancy could vanish also in extended system. We present a detailed angular-dependent study of magnetization reversal dynamics of a thin film with well-defined uniaxial magnetic anisotropy, performed over 9 decades of applied field sweep rate (dH/dt). The angular-dependent properties display a gradual transition from domain wall pinning and motion-like behaviour to a nucleative single-particle one, as dH/dt increases. Remarkably, in the high dynamic regime, where nucleation of reversed domains is the dominant mechanism of the magnetization reversal (nucleative regime), the magnetic properties including the astroid become closer to the ones predicted by SW model. The results also show why the SW model can successfully describe other extended systems that present nucleative regime, even in quasi-static conditionsThis work has been supported by MINECO (Ministerio de Economía y Competitividad) through Projects No. MAT2012-39308, FIS2015-67287-P, and FIS2016-78591-C3-1-R, by the Comunidad de Madrid through Project S2013/MIT-2850 NANOFRONTMAG-CM, and by MINECO through the FLAGERA Programme of Graphene Flagship: SOgraph project (No. PCIN-2015-216); and M-era.Net Programme: NEXMAG project (PCIN- 2015-126). IMDEA-Nanociencia acknowledges support from the ‘Severo Ochoa’ Program for Centres of Excellence in R&D (MINECO, Grant SEV-2016-0686). P.P. acknowledges support through the Marie Curie AMAROUT EU Programme and JCI-2011-09602. A.B. acknowledges MINECO through the ENMA-National project (MAT2014-56955-R)

Aislaciones en climas fríos

Independientemente de la fuente que provee energía térmica a un edificio, es necesario aislarlo a fin de aumentar su eficiencia energética. En el presente trabajo se evalúa el comportamiento de los cerramientos aislados de los edificios ante la acción de los procesos de transferencia de masa y de calor que en ellos ocurren. En función de este conocimiento y la aplicación de un modelo apropiado se pretende configurar una estructura de aislaciones que permita la predicción de los efectos perjudiciales que producen la condensación de vapor de agua interna o la formación destructiva de hielo. Se incluyen aplicaciones a sistemas de aislación habituales con materiales de uso corriente en la construcción local, que contradicen viejos preconceptos sobre el tema.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Searching for glycosylated natural products in actinomycetes and identification of novel macrolactams and angucyclines

Many bioactive natural products are glycosylated compounds in which the sugar components usually participate in interaction and molecular recognition of the cellular target. Therefore, the presence of sugar moieties is important, in some cases essential, for bioactivity. Searching for novel glycosylated bioactive compounds is an important aim in the field of the research for natural products from actinomycetes. A great majority of these sugar moieties belong to the 6-deoxyhexoses and share two common biosynthetic steps catalyzed by a NDP-D-glucose synthase (GS) and a NDP-D-glucose 4,6-dehydratase (DH). Based on this fact, seventy one Streptomyces strains isolated from the integument of ants of the Tribe Attini were screened for the presence of biosynthetic gene clusters (BGCs) for glycosylated compounds. Total DNAs were analyzed by PCR amplification using oligo primers for GSs and DHs and also for a NDP-D-glucose-2,3-dehydratases. Amplicons were used in gene disruption experiments to generate non-producing mutants in the corresponding clusters. Eleven mutants were obtained and comparative dereplication analyses between the wild type strains and the corresponding mutants allowed in some cases the identification of the compound coded by the corresponding cluster (lobophorins, vicenistatin, chromomycins and benzanthrins) and that of two novel macrolactams (sipanmycin A and B). Several strains did not show UPLC differential peaks between the wild type strain and mutant profiles. However, after genome sequencing of these strains, the activation of the expression of two clusters was achieved by using nutritional and genetic approaches leading to the identification of compounds of the cervimycins family and two novel members of the warkmycins family. Our work defines a useful strategy for the identification new glycosylated compounds by a combination of genome mining, gene inactivation experiments and the activation of silent biosynthetic clusters in Streptomyces strains

Genetic mapping for agronomic traits in a MAGIC population of common bean (Phaseolus vulgaris L.) under drought conditions

Background Common bean is an important staple crop in the tropics of Africa, Asia and the Americas. Particularly smallholder farmers rely on bean as a source for calories, protein and micronutrients. Drought is a major production constraint for common bean, a situation that will be aggravated with current climate change scenarios. In this context, new tools designed to understand the genetic basis governing the phenotypic responses to abiotic stress are required to improve transfer of desirable traits into cultivated beans. Results A multiparent advanced generation intercross (MAGIC) population of common bean was generated from eight Mesoamerican breeding lines representing the phenotypic and genotypic diversity of the CIAT Mesoamerican breeding program. This population was assessed under drought conditions in two field trials for yield, 100 seed weight, iron and zinc accumulation, phenology and pod harvest index. Transgressive segregation was observed for most of these traits. Yield was positively correlated with yield components and pod harvest index (PHI), and negative correlations were found with phenology traits and micromineral contents. Founder haplotypes in the population were identified using Genotyping by Sequencing (GBS). No major population structure was observed in the population. Whole Genome Sequencing (WGS) data from the founder lines was used to impute genotyping data for GWAS. Genetic mapping was carried out with two methods, using association mapping with GWAS, and linkage mapping with haplotype-based interval screening. Thirteen high confidence QTL were identified using both methods and several QTL hotspots were found controlling multiple traits. A major QTL hotspot located on chromosome Pv01 for phenology traits and yield was identified. Further hotspots affecting several traits were observed on chromosomes Pv03 and Pv08. A major QTL for seed Fe content was contributed by MIB778, the founder line with highest micromineral accumulation. Based on imputed WGS data, candidate genes are reported for the identified major QTL, and sequence changes were identified that could cause the phenotypic variation. Conclusions This work demonstrates the importance of this common bean MAGIC population for genetic mapping of agronomic traits, to identify trait associations for molecular breeding tool design and as a new genetic resource for the bean research community